For the past 4 years, the Mailman School of Public Health of Columbia University has had an NCI-funded R25T Training Program for cancer investigators in Population Sciences. Like our longstanding T32 program, the R25 program is a collaboration of faculty in three departments: Epidemiology, Biostatistics, and Environmental Health Sciences. Increasingly, investigators in cancer-related population sciences require not only expertise in their own specific disciplines but a broad-based multidisciplinary perspective, including a more than superficial understanding of molecular genetics, clinical oncology, toxicology, health services and health outcomes research, and behavioral sciences. The R25 provides 6 trainees (3 pre- and 3 postdoctoral) annually with cross-disciplinary education in cancer prevention and control, an in-depth research experience, and access to a large faculty in the population sciences with numerous funded research projects in cancer. Graduates of the program have gone on to prestigious academic and research positions. In this competing renewal, we propose to extend our program by providing more training in clinical cancer genetics, health economics, and the basic biology of cancer. In addition to required and recommended courses within the School of Public Health, our program offers an innovative specialized curriculum, with 2-month individualized modules in year 2 giving trainees hands-on experience in: data collection and interviewing in a clinical setting;behavioral research;laboratory research;health services and outcomes;clinical oncology, and data analysis. Each trainee is required to take courses in pathology, research ethics, and research funding;to undertake an in-depth multidisciplinary project with a focus in his/her specialty;and to make two presentations/year at a multidisciplinary weekly conference. Trainees have the opportunity to attend cancer meetings and meetings in their discipline and are encouraged but not required to make presentations at those meetings. Postdoctoral trainees are required to submit research grant proposals for mock peer review by the faculty. For this specialized program, we propose to reduce our trainees from 6 (3 pre-, 3 postdoctoral) to 5 (1 pre-, 4 postdoctoral);to add a Program Coordinator for day-to- day operations;to implement a more detailed evaluation plan;and to add to our Advisory Committee, which oversees recruitment, performance and evaluation of the trainees, an external advisory committee of three outstanding scientist/educators. Our R25 Training Program utilizes the rich research environment of the Herbert Irving Comprehensive Cancer Center, New York Presbyterian Hospital, Harlem Hospital, the Washington Heights/Harlem communities, and New York City.